4.9 Famoxadone (208)(T,R)*

T- toxicological evaluation; R-residue and analytical aspects
*New compound

TOXICOLOGY

Famoxadone is the ISO approved common name for 5-methyl-5-(4-phenoxyphenyl)-3-phenylamino-2,4-oxazolidinedione. It is a racemic mixture containing two enantiomers in a 50: 50 ratio. The mechanism of antifungal action of famoxadone is inhibition of the mitochondrial respiratory chain at complex III, which results in decreased production of ATP.

Famoxadone has not been evaluated previously by JMPR. Consequently, famoxadone is being reviewed at the present Meeting in the context of the JMPR New Compounds Review Programme.

Studies in rats show that about 40% of the administered dose of radiolabelled famoxadone is absorbed and rapidly eliminated from the body in the faeces (> 75% in 24 h) and urine (about 10% in 24 h). Most of the administered dose found in the faeces is unmetabolized famoxadone. In rats, absorption from the gastrointestinal tract becomes the limiting factor for internal exposure at doses greater than about 800 mg/kg bw. It appeared that there were no important differences in metabolism between dogs and rats, within the limits imposed by the different doses used, and that there were no significant differences between male and female rats (only males having been used in the experiments with dogs). The primary metabolic pathway involved the hydroxylation of the parent molecule to the corresponding mono- and di-hydroxylated derivatives, which were only recovered from the faeces. Metabolites resulting from the cleavage of the oxazolidinedione ring moiety were recovered from the urine. A sulphate was the major urinary metabolite containing the phenoxyphenyl moiety, whereas 4-acetoxyaniline was the major urinary metabolite containing the phenylamino moiety. No parent famoxadone was detected in the urine.

Famoxadone has low acute toxicity when administered by oral, dermal, and inhalation routes. The acute LD₅₀ after oral administration is > 5000 mg/kg bw in rats and the LD₅₀ after dermal administration is > 2000 mg/kg bw in rabbits. The LC₅₀ in rats after 4 h is > 5300 mg/m³, the only concentration tested. Famoxadone produces transient mild dermal irritation and transient mild eye irritation, but does not cause skin sensitization.

In short-term studies of oral administration in rodents, dogs and non-human primates, and long-term studies of oral administration in rodents, NOAELs were based on effects on body weight and nutrition, mild haemolytic anaemia, and/or mild to moderate liver toxicity. Mild regenerative haemolytic anaemia was found in rats, mice, dogs and monkeys, as indicated by decreased erythrocyte counts, haemoglobin and/or haematocrit, increased reticulocyte counts, or other related changes in haematological parameters. Methaemoglobin was not measured. Secondary effects of anaemia were also found in the spleen (e.g. increased spleen weight, deposition of haemosiderin pigment, extra-medullary haematopoiesis), in the bone marrow (compensatory erythropoiesis), and in the liver (increased Kupffer cell pigment, increased bile pigment). In studies involving repeated dosing, anaemia was found to occur early in the study and often appeared to be compensated for later. In an experiment in which rats were fed famoxadone at a single dose level of 800 ppm, equal to 61.6 mg/kg bw per day, blood samples were taken at multiple timepoints. Mild anaemia was observed after 30 days, but not after 16 days. Famoxadone also induced hepatocellular responses that are normally considered to be adaptive (e.g. enlarged livers, increased liver weights and liver: body-weight ratios, hepatocellular hypertrophy). These adaptive responses were characterized by increased quantities of cytochrome P-450 and/or increased rates of peroxisomal b-oxidation. Hepatotoxicity, which was mild, was observed only at higher doses and was characterized by mild histopathological lesions (e.g. single cell or focal necrosis, hepatocellular degeneration, diffuse fatty change, eosinophilic foci) and marginally elevated concentrations of blood enzymes suggestive of liver damage. The NOAELs after short-term oral administration were 62.4 mg/kg bw per day in mice treated for 3 months, 13 mg/kg bw per day in rats treated for 3 months, 1.2 mg/kg bw per day in dogs treated for 1 year and 100 mg/kg bw per day in cynomolgus monkeys treated for 1 year.

Long-term studies in rats (2 years) and mice (18 months) show little evidence of irreversible organ toxicity, although chronic dietary exposure of female mice increased the incidence of generalized amyloidosis. Other effects that were observed, some of which formed the basis for the NOAEL values, were reductions in body-weight gain, hepatotoxicity and mild regenerative anaemia. The NOAELs for long-term toxicity were 700 ppm, equal to 96 mg/kg bw per day, in mice, and 200 ppm, equal to 8.4 mg/kg bw per day, in rats. Famoxadone did not demonstrate any evidence of carcinogenic potential at doses up to the highest tested, which were 400 ppm, equal to 17 mg/kg bw per day, in rats and 7000 ppm, equal to 96 mg/kg bw per day, in mice.

Famoxadone was tested for genotoxicity in an adequate range of studies, both in vitro and in vivo. The results observed were largely negative. Although famoxadone produced a weak clastogenic effect in an in vitro study, the Meeting did not consider this to be toxicologically significant.

The Meeting concluded that famoxadone is unlikely to pose a genotoxic risk to humans.

Because the results of the studies of carcinogenicity were negative, the Meeting concluded that famoxadone is unlikely to pose a carcinogenic risk to humans.

In a two-generation study of reproductive toxicity in rats, the NOAEL for adult rats and their offspring was 200 ppm, equal to 11.3 mg/kg bw per day in adults, on the basis of systemic toxicity in the parental rats and reduced bodyweight gain in the offspring at a dose of 800 ppm, equal to 45 mg/kg bw per day; no other signs of reproductive toxicity were observed at this dose, the highest tested. In studies of developmental toxicity in rats and rabbits, no effects were observed in fetuses at doses of 1000 mg/kg bw per day, the highest dose tested. The results from the two studies of developmental toxicity and the study of reproductive toxicity did not demonstrate any increased susceptibility of fetuses or pups to famoxadone.

In 28-day studies of immunotoxicity in rats and mice, no evidence of immunotoxicity was found in rats receiving doses in the diet of 800 ppm, equal to 55 and 57 mg/kg bw per day in males and females respectively, or in mice receiving doses in the diet of 7000 ppm, equal to 1664 mg/kg bw per day in females, the highest doses tested. In male mice, there was a minimal but significant reduction in the primary humoural response to sheep erythrocytes at a dose of 7000 ppm; the NOAEL for this activity in male mice was thus 2000 ppm, equal to 327 mg/kg bw per day. The toxicological significance of this effect was considered to be minimal.

Clinical and microscopic evidence of lens opacities were clearly observed in female and male dogs (in both the 3month and 1-year studies), at doses below those at which any other effects were observed in any other species. The mechanism by which these effects are induced is not understood.

Famoxadone does not appear to be neurotoxic. Some observations of minor effects made in an experiment investigating acute neurotoxicity were attributed to general malaise. Other than some clinical observations in males and females fed with the high dose of famoxadone in the 3month study in dogs (myotonic twitching, possibly a result of high concentrations of serum potassium), no evidence for neurotoxicity was found in any other studies of toxicity, including a short-term study of neurotoxicity in rats.

The Meeting concluded that the existing data were adequate to characterize the potential hazard to fetuses, infants and children.

Toxicological evaluation

An ADI of 0-0.006 mg/kg bw was established for famoxadone on the basis of the NOAEL of 1.2 mg/kg bw per day in a 1-year study in dogs treated by gavage, with a safety factor of 200; an extra safety factor was added because this study in dogs is not viewed as a long-term study. The critical effect was the occurrence of cataracts in dogs at 300 ppm, equal to 8.8 mg/kg bw per day; some of these cataracts developed late in the study, indicating that progression might have been possible, had a long-term study been conducted.

The Meeting established an acute RfD of 0.6 mg/kg bw for famoxadone on the basis of a NOAEL of 61.6 mg/kg bw per day for 16 days, the only dose tested, in a study of haematotoxicity in rats and a safety factor of 100 (see general item 2.2).

A toxicological monograph was prepared. G3

Levels relevant to risk assessment

^a Diet
^b Gavage
^c Highest dose tested

Estimate of acceptable daily intake for humans

0-0.006 mg/kg bw

Estimate of acute reference dose

0.6 mg/kg bw

Studies that would provide information useful to the continued evaluation of the compound

- Observations in humans
- Investigation of species differences in erythrocyte sensitivity to haemolysis
- Investigation of the mechanisms by which cataracts are formed in dogs

Summary of critical end-points for famoxadone

RESIDUE AND ANALYTICAL ASPECTS

Famoxadone is an oxazolidinedione fungicide belonging to the quinol inhibitor family, which inhibits mitochondrial respiration of fungi. The compound was scheduled at the 33rd Session of the CCPR (ALINORM 01/24A) for evaluation by the 2003 JMPR as a new compound. Data on metabolism and environmental fate, methods of residue analysis, supervised trials on grapes, melons, cucumbers, tomatoes, potatoes, barley and wheat, a cow feeding study and the fate of residues in processing were reported. Information on GAP, national MRLs and residue data was reported by the governments of Germany, The Netherlands and Poland.

IUPAC name: 3-anilino-5-methyl-5-(4-phenoxyphenyl)-1,3-oxazolidine-2,4-dione
Chemical Abstracts name: 5-methyl-5-(4-phenoxyphenyl)-3-(phenylamino)-2,4-oxazolidinedione

Metabolism in animals

Metabolism studies were conducted with [¹⁴C]famoxadone labelled in the phenoxyphenyl and the phenylamino moieties.

Rats given single or multiple oral doses of 5 and 100 mg/kg body weight of ¹⁴C famoxadone excreted between 88.8 and 96% of the administered radioactivity in the faeces and from 3 to 12% in the urine, most within 24 h. Famoxadone was the major component in faeces, and the monohydroxy derivative in the phenoxyphenyl and the dihydroxy in the phenoxyphenyl and phenylamino moieties the main metabolites, each representing up to 13% of the administered dose. In urine, only hydrolytic and cleavage products were detected, including 4-aminophenyl acetate (4-acetoxyaniline), at up to 7% of the administered dose. When [¹⁴C]famoxadone was given to biliary-cannulated rats in a single oral dose of 5 mg/kg bw, excretion in bile ranged from 30 to 39% and in faeces from 56 to 65% of the administered dose. Famoxadone was the only labelled component in faeces, and it was not detected in the bile. The main metabolites released in bile treated with b-glucuronidase/sulfatase were the mono-hydroxylated compound, the catechol 1,2 dihydroxybenzene and a hydrolysis cleavage product (a-hydroxy-4-(4-hydroxyphenoxy)- a -methylbenzeneacetic acid), none higher than 6% of the administered dose.

Lactating goats dosed orally for 7 days at the equivalent of 10 ppm in the diet excreted most of the radioactivity (>80%) in the faeces. Famoxadone was the major radioactive component in milk and tissues. Radioactive residues in milk reached a plateau at day 6-7, with up to 0.025 mg/kg ¹⁴C famoxadone equivalents. On average, famoxadone was present in muscle at 0.009 mg/kg, in fat at 0.086 mg/kg, in liver at 0.025 mg/kg, in kidney at 0.011 mg/kg and in milk at 0.006 mg/kg, representing from 18.5 to 57.5% of the TRR in each matrix. Mono- and dihydroxylated metabolites were detected in either faeces or liver at up to 4.8% of the TRR. Individual components released by protease digestion and the remaining unextractable residues were <0.05 mg/kg.

Laying hens dosed for 7 consecutive days at a dietary level of 10 ppm excreted most of the radioactivity in faeces (>88%). Eggs accounted for <0.04% and tissues for <0.15% of the administered dose. Radioactive residues were equivalent to <0.01-0.067 mg/kg in the egg yolk and 0.06-0.3 mg/kg in liver. No residues (<0.01 mg/kg famoxadone equivalents) were detected in muscle, skin or egg white. Famoxadone was the major component in the excreta (up to 17.8% of the TRR), followed by the polar metabolite 5-(4-hydroxyphenyl)-5-methyloxazolidine-2,4-dione (15.4% of the TRR) The major radioactive compound in egg yolk and liver was the mono-hydroxylated compound (up to 0.08 mg/kg famoxadone equivalents). No radioactive famoxadone was detected in liver.

In summary, famoxadone accumulation in animals is low, with most of the administered radioactivity being excreted in faeces. The metabolism includes hydroxylation of the phenoxyphenyl and phenylamino rings, hydrolytic cleavage of the oxazolidinedione moiety, and cleavage of the hydrazine bond and the phenoxyphenyl ether linkage. Low levels of famoxadone or metabolites were found in goat and poultry tissues, milk and eggs.

In plants

When grape vines were treated with a simulated WG formulation of [¹⁴C]famoxadone (3 times at 0.3 kg ai/ha) most of the radioactivity was recovered from the surface of the leaves and fruits (79 to 98% of the TRR), with >95% of the residue identified as famoxadone. A minor metabolite, 1-(4-phenoxyphenyl)ethanone, was also observed (<2%). In the fruit, famoxadone residues reached a maximum of 0.03 mg/kg equivalents at day 14.

Tomato plants were treated twice with a simulated WG formulation of [¹⁴C]famoxadone at a rate of 0.63 kg ai/ha. Most of the radioactivity was extracted with acetone (about 80% of the TRR). On average, more than 90% of the residue was famoxadone and no significant metabolites were identified (<10% of the TRR). At 14 days the residue of famoxadone in tomato fruit was 0.07 mg/kg.

When potato plants were treated in a greenhouse 3 times at 0.3 kg ai/ha with a WG of [¹⁴C]famoxadone most of the applied radioactivity was recovered in the acetone wash of the foliage surface (mean of 86.5 and 61.8% at days 37 and 51). 76-95% of the residue was characterized as famoxadone. Two minor hydrolytic metabolites were observed, 1-(4-phenoxyphenyl)ethanone and a-hydroxy-a-methyl-4-phenoxybenzeneacetic acid 2-phenylhydrazide, accounting for <5% of the total radioactivity. Negligible systemic translocation of radiolabelled residues to the tubers was found (<0.01 mg/kg famoxadone equivalent).

In mature wheat plants from a field harvested 50 days after the last of 3 applications at 0.2 kg ai/ha of EC [¹⁴C]famoxadone low levels of ¹⁴C residues were detected in the grain (0.01-0.02 mg/kg equivalents). Most of the radiolabelled residues (>98%) were found in the straw (average 3.4 mg/kg). Famoxadone was the main component (average 0.36 mg/kg ¹⁴C equivalents) of the extractable residues in the foliage and mature straw. The main metabolites were monohydroxy-famoxadone (0.24 mg/kg famoxadone equivalents in straw at day 72), dihydroxy-famoxadone (0.30 mg/kg famoxadone equivalents in foliage at day 29) and a conjugation product (0.26 mg/kg famoxadone equivalents in foliage at day 29).

In summary, famoxadone was the main compound found in treated grapes, tomatoes and potatoes. Little translocation of the radioactivity to potato tubers was found and residues in wheat grain were low. Metabolism in wheat plants was significant, mainly through hydroxylation and conjugation.

Environmental fate

The degradation of famoxadone in soils under aerobic conditions showed half-lives varying from 2 days in silt loam to 11 days in sandy loam. The DT₉₀ was 134 days. Famoxadone was not detected in the unextractable residues subjected to strong acidic treatments. Approximately 79.4 to 93.3% of the parent compound remained after 90 days in sterile soil, indicating that famoxadone is degraded mainly by microbes. The major degradation product was the phenoxyphenyl-hydroxylated famoxadone (IN-KZ007), with a peak of 7 to 16% within 4 days, and the hydrolysis cleavage product a-hydroxy-a-methyl-4-phenoxybenzeneacetic acid (IN-JS940) which reached a peak of 11% of the applied radioactivity. The half-life of IN-KZ007 and IN-JS940 in soils varied from 3.2 to 15 days and 6 to 23 h respectively.

Under field conditions in the USA and Canada, unquantifiable or low residues of famoxadone were found below the 15 cm depth, showing low mobility in soil. The half-life in various soils varied from 5 to 28 days.

One rotation crop study was reported to the Meeting. Soils treated once or three times with famoxadone at 0.4 kg ai/ha were aged under greenhouse conditions for 30, 120 and 365 days before planting different crops. Famoxadone residues were detected in lettuce, sugar beet roots, wheat forage and straw (0.02 to 0.06 mg/kg equivalents), but not in sugar beet tops or wheat grain (<0.01 mg/kg eq). Average residues in treated soils were 0.26 and 0.04 mg/kg famoxadone equivalents at days 30 and 120 respectively. No famoxadone was detected in crops or soil after 365 days. On average, crop:soil residue ratios were 0.11 in lettuce, 0.19 in sugar beet, 0.10 in wheat foliage and 0.58 in wheat straw. When these ratios were applied to an average field soil famoxadone residue of 0.09 mg/kg, found 14 days after the last of 8 applications at 0.18 kg ai/ha (twice GAP) in a supervised trial on potatoes in Italy, the calculated residues of famoxadone in lettuce, sugar beet and wheat, after application to potatoes, ranged from 0.01 mg/kg in lettuce and wheat foliage to 0.05 mg/kg in wheat straw.

In summary, famoxadone is degraded in soil by microbes, with a half-life up to 28 days in the field, mainly through hydroxylation. The compound has low mobility and low translocation to crops in soils containing aged residues.

Residue analysis

Famoxadone can be extracted from crops with acetonitrile/water. The extract is partitioned with hexane and famoxadone quantified by reversed phase HPLC with UV detection or HPLC/MS (positive thermospray). The LOQ is 0.02 mg/kg for grapes and cereal grain and 0.05 mg/kg for cereal straw and forage. Average recoveries of famoxadone at levels from 0.02 to 0.5 mg/kg ranged from 74 to 109% with a maximum RSD of 21% (3 samples at each level).

Clean-up on a Florisil/sodium sulfate SPE column can follow the extraction before quantification by column-switching HPLC on a phenyl column followed by a C-18 column, with UV detection. The LOQ is 0.02 mg/kg. Average recoveries from tomato fruit, purée and paste at 0.02 and 0.12 mg/kg ranged from 82 to 93%, with a maximum RSD (n=3) of 21%. Extraction of incurred residues from tomato samples with acetonitrile/water showed an average extraction efficiency of 110% compared with the method used in the metabolism study described above.

In another method, samples are extracted with acetone/water, the extract cleaned up on GPC and silica gel columns, and famoxadone determined by GC with an ECD. The limit of quantification is 0.05 mg/kg for raisins and tobacco, 0.02 mg/kg for grapes and cucumbers and 0.01 mg/kg for wine, potatoes and wheat grain. Average recoveries at levels from 0.01 to 0.5 mg/kg ranged from 76 to 106%, with maximum RSD of 9.5% (5 samples at each level).

Samples of milk, eggs and animal tissues can be extracted with ACN/water, partitioned with hexane, cleaned up on a Florisil SPE column and analysed by GC with an NPD. Average recoveries from beef muscle and fat, milk, poultry muscle and eggs at 0.02 and 0.5 mg/kg ranged from 85 to 107%, with an RSD of 4 to 12% (n=3 at each level).

In a method for analysing animal tissues, the sample is mixed with C-18 packing, the mixture is washed with hexane and famoxadone is eluted with acetonitrile. The eluate is filtered through a bed of basic alumina and the extract is passed through graphitized carbon followed by silica SPE columns. Famoxadone is determined by column-switching HPLC (phenyl and C-18 columns) with UV detection. The LOQ is 0.01 mg/kg for whole milk, skimmed milk, cream and whole egg and 0.05 mg/kg for bovine liver. Recoveries ranged from 70 to 105% at 0.01 to 2.0 mg/kg fortification levels. This method was proposed for regulatory use. The extraction efficiencies of this method for incurred radiolabelled famoxadone residues found in milk, liver and fat in a goat metabolism study, compared to the method used in the study (extraction with acetonitrile and clean-up by C-18 SPE) were ³87.4%.

Stability of residues in stored analytical samples

The stability of famoxadone in grapes, potatoes, wheat forage, straw, grain and soil fortified at 1 mg/kg and stored at -20°C was determined. After 18 months, 70% (in wheat grain and straw) to 99% (in grapes) of the famoxadone remained in the samples. Famoxadone at 0.3 mg/kg was stable in tomatoes and peppers after 18 months (110 and 107% remained respectively) and in cucumbers after 10 months (102% remaining). It was also stable in tomato paste at 1 mg/kg and tomato purée (0.3 mg/kg) stored at -10°C, with 93 and 89% of the residues remaining after 18 months. Two studies on potatoes showed different results for the stability of famoxadone. In one, residues dropped to half after 3 months in samples fortified with 1 mg/kg. In the other, conducted with a supervised trial on potatoes, residues were stable up to 10.5 months at 0.3 mg/kg. The analytical recoveries in both studies were at acceptable levels.

The storage stability of famoxadone was evaluated in whole milk samples fortified with 0.1 mg/l and in muscle and liver samples containing incurred residues from a feeding trial. The average percentage of famoxadone remaining in milk after 117 days was 87%, and residues in muscle (0.072 mg/kg) did not change significantly from day 21 to day 138. In liver, residues were 0.069 ± 0.010 mg/kg at day 21 and 0.065 ± 0.023 mg/kg at day 139.

Definition of the residue

Metabolism studies showed that famoxadone was the main radiolabelled residue in vegetable crops, milk and cow tissues. In egg yolk and hen liver, a monohydroxylated metabolite was the major residue, but present at low concentration. Famoxadone concentrates in the fat of treated goats and in egg yolk. In a cow feeding study, to be described later, residues also concentrated in fat and cream. Famoxadone has a log K_OW of 4.65.

The Meeting agreed that the definition of the famoxadone residue for compliance with MRLs and for dietary intake estimations in plant and animal commodities should be famoxadone. The compound is fat-soluble.

Results of supervised trials

Grapes. Famoxadone can be used on grapes in Europe at a maximum application rate of 0.05 kg ai/ha (France and Greece), 0.09 kg ai/ha (Italy and Spain) or 0.144 kg ai/ha (Germany). Spain and Greece allow a maximum of 6 applications per season and the other countries a maximum of 3 applications, except Germany (8). The PHI in all countries is 28 days (40 days in Italy for formulations with fosestyl-Al).

A total of 25 trials using 10 to 12 applications, with a 7-day interval, were conducted in these countries between 1995 and 1999, at 0.05 to 0.146 kg ai/ha. The initial application was at flowering. The varieties used in the trials were mainly for the production of wine. In five decline studies residues decreased by 61.8%, on average, from day 1 to day 30 after the last application.

Residues within about 28 days PHI were 0.19 (2), 0.25, 0.24, 0.29, 0.37, 0.46, 0.48 (3), 0.50 (2), 0.54, 0.55, 0.56, 0.62, 0.66 (2), 0.74, 0.90 (2), 0.98, 1.0, 1.2 and 1.5 mg/kg.

The Meeting agreed that with applications starting at flowering it is unlikely that the first applications would influence the residue levels, and that all the trials conducted at GAP rate and PHI in Europe should be considered for the estimations.

The Meeting estimated a maximum residue level of 2 mg/kg, an STMR of 0.54 mg/kg and an HR of 1.5 mg/kg for famoxadone in grapes.

Cucumber and summer squash. The current Italian label indicates that famoxadone may be applied to cucumbers at 0.112 kg ai/ha at flowering, followed by 2 applications at the same rate (maximum of 3 applications) with a minimum 1-week interval, with a 10-day PHI. This label applies also to zucchini (summer squash) and melons. The label does not give any explicit restriction to the use under protected conditions. There is no GAP for famoxadone in Greece or Spain.

Ten trials were conducted on protected cucumbers using 5 applications at 0.065 to 0.118 kg ai/ha (1 week interval) in Italy, Greece and Spain in 2001. Decline studies showed residues decreasing by 39%, on average, from day 1 to day 7 after the last application. Residues at 7 days PHI were 0.01 (2), 0.02 (3), 0.03 (2), 0.05 (2) and 0.10 mg/kg.

The Meeting agreed that, as cucumbers under protected conditions grow quickly, it is unlikely that the higher number of applications used in the trials would influence the residue within a 10-day PHI. The Meeting also agreed to evaluate the trials conducted in Greece and Spain against Italian GAP and extrapolate the recommendations to summer squash.

The Meeting estimated a maximum residue level of 0.2 mg/kg, an STMR of 0.025 mg/kg and an HR of 0.10 mg/kg for famoxadone in cucumber and summer squash.

Melons. In Italy, famoxadone GAP for cucumbers also applies to melons. There is no GAP for famoxadone use on melons in Greece, France or Spain. Twenty trials were conducted on melons using 5 applications at about the Italian rate in Italy, Greece, France and Spain either in the glasshouse or in the field in 1991. No significant difference in residue levels was found between the glasshouse and field trials. Residues 7 days after the last application ranged from 0.02 to 0.22 mg/kg in whole fruit. Residues in pulp were <0.01 or 0.01 mg/kg from day 1 to 7, and in one sample the residue 2 h after the last application was 0.22 mg/kg.

As the trials were not according to GAP (too many applications), the Meeting agreed not to recommend an MRL of famoxadone in melons.

Tomato. Thirty-six trials were conducted in Europe on tomatoes, where maximum GAP is 0.09 kg ai/ha in France, Spain and Greece and 0.11 kg ai/ha in Italy. France and Spain allow up to 4 applications and a PHI of 3 days. Italy allows 3 applications and 10 days PHI or 6 applications of a lower rate (0.005 kg ai/ha) and 3 days PHI. Greece allows 8 applications and 3 days PHI. Trials were conducted using 5 or 7 applications at 0.07 to 0.137 kg ai/ha, with a PHI of 3 days or decline studies from 0 to 7 or 14 days.

Six trials conducted in the south of France according to French GAP gave residues at 3 days PHI of 0.03, 0.08, 0.10 (2), 0.12 and 0.15 mg/kg, and three with 7 applications complying with GAP in Greece showed residues of 0.08, 0.10 and 0.15 mg/kg.

In Greece, 3 trials according to Greek GAP (7 applications) and 4 trials according to Italian GAP (5 applications) gave residues at 3 days PHI of 0.04, 0.09, 0.10, 0.11(2), 0.15 and 0.16 mg/kg.

In Italy, eleven trials with 5 or 7 applications matching either Greek or Italian GAP gave residues at 3 days PHI of 0.02 (2), 0.03 (3), 0.04, 0.05, 0.18, 0.33, 0.74 and 1.1 mg/kg.

In Spain, 5 trials with 7 applications which matched Greek GAP and 3 trials according to Spanish GAP gave residues at 3 days PHI of 0.02, 0.04, 0.05 (2) 0.07, 0.10, 0.12 and 0.18 mg/kg. One trial conducted at 0.131-0.137 kg ai/ha gave residues of 0.20 mg/kg.

Thirty six trials conducted according to GAP in Europe gave residues, in rank order, of 0.02 (3), 0.03 (4), 0.04 (3), 0.05 (3), 0.07, 0.08 (2), 0.09, 0.10 (5), 0.11(2), 0.12 (2), 0.15 (3), 0.16, 0.18 (2), 0.20, 0.33, 0.74 and 1.1 mg/kg.

The Meeting estimated a maximum residue level of 2 mg/kg, an HR of 1.1 mg/kg and an STMR of 0.10 mg/kg for famoxadone in tomato.

Potato. Famoxadone can be applied in Europe with a 14 days PHI. The application rate is 0.09 kg ai/ha in Greece, Italy and Spain (up to 8, 6 and 4 applications respectively), 0.175 kg ai/ha in the UK and Germany (12 and 6 applications respectively) and up to 6 application at 1.15 kg ai/ha in Belgium. There is no approved GAP in Denmark or France. In 12 trials conducted in Europe at a higher rate (6 to 12 applications at 0.164 to 0.224 kg ai/ha), residues at 14 days PHI were <0.02 mg/kg.

A metabolism study on potatoes with 3 applications of 0.3 kg ai/ha showed <0.01 mg/kg famoxadone equivalents in tubers.

Data from supervised trials conducted at higher rates and from the metabolism study support the conclusion that no residues are to be expected in potato tubers after the plants are treated with famoxadone according to good agriculture practices.

The Meeting agreed to recommend an MRL of 0.02* mg/kg, and estimated an HR and an STMR of 0 mg/kg for famoxadone in potato.

Barley. The current UK label indicates that famoxadone may be applied once or twice before quarter ear emergence to barley as a foliar spray at a maximum rate of 0.150 kg ai/ha. In Belgium, only 1 application is allowed, with a 28 days PHI. Sixteen trials using two foliar applications at 0.15 or 0.20 kg ai/ha were conducted in Belgium, France, Germany and the UK. Samples were collected at maturity, 32-78 days after the last application.

Twelve trials conducted with winter barley matching the UK GAP rate gave residues of <0.02 (8), 0.04 (2), 0.08 and 0.11 mg/kg 32 to 78 days after the last application. Four trials conducted at 0.2 kg ai/ha gave residues of <0.02 to 0.18 mg/kg.

The Meeting estimated a maximum residue level of 0.2 mg/kg and an STMR of 0.02 mg/kg for famoxadone in barley.

Wheat. The current UK label indicates that famoxadone may be applied to winter wheat before flowering as a foliar spray up to 3 times at a maximum rate of 0.150 kg ai/ha, with a maximum of 0.45 kg ai/ha per season. In Belgium, GAP is one application of 0.15 kg ai/ha and 28 days PHI. Fifteen trials were conducted in Belgium, France, Germany and the UK. In 10 trials with 1 application of 0.28 kg ai/ha and 2 of 0.15 kg ai/ha, samples harvested at maturity, between 36 and 66 days after the last application, gave residues of <0.02 (9) and 0.04 mg/kg in grain. The Meeting agreed that it is unlikely that the higher rate in the first application would influence the residues in the grain at a mature stage, and evaluated these trials. In 5 trials with 3 sprays of 0.20 kg ai/ha, residues were in the same range (<0.02-0.06 mg/kg).

The Meeting estimated a maximum residue level of 0.1 mg/kg and an STMR of 0.02 mg/kg for famoxadone in wheat.

Barley straw and forage. In twelve trials within the GAP rate, residues in barley straw harvested at maturity (32-78-day PHI) were 0.16, 0.19, 0.34, 0.47, 0.85, 0.86, 0.93, 0.96, 1.4, 1.5, 2.5 and 3.8 mg/kg. Allowing for 88% DM (FAO Manual, 2002), the median and the highest residues in barley straw are 0.99 (0.895/0.88) and 4.2 mg/kg (3.8/0.88) respectively. Trials at higher rates gave residues from 0.35 to 3.9 mg/kg. Forage samples were harvested in two trials at 7, 14 and 21 days after the last application. Residues after 7 days were 1.4 and 1.8 mg/kg.

The Meeting estimated a maximum residue level of 5 mg/kg and an STMR of 0.99 mg/kg for famoxadone in barley straw.

As too few trials were conducted, the Meeting agreed not to estimate a maximum residue level for famoxadone in barley forage.

Wheat straw and forage. In ten trials within the GAP rate, residues in wheat straw harvested at maturity (34-45 days PHI) were 0.55, 1.2, 1.6, 1.7, 2.0, 2.1, 2.5, 2.7, 2.9 and 4.3 mg/kg. Allowing for 89% DM (FAO Manual, 2002), the median and the highest residues in wheat straw are 2.28 (2.05/0.89) and 4.8 mg/kg (4.3/0.89) respectively. Residues from 5 trials at a higher rate gave residues from 3.4 to 11 mg/kg. Wheat forage samples were harvested in two trials at 0, 7, 14 and 21 days after the last application. The residues at 0 days were 4.2 and 5.8 mg/kg.

The Meeting estimated a maximum residue level of 7 mg/kg and an STMR of 2.28 mg/kg for famoxadone in wheat straw.

There were too few trials to recommend a maximum residue level for famoxadone in wheat forage.

FATE OF RESIDUES IN PROCESSING

Grapes from vines treated with famoxadone were vinified by traditional French wine-making techniques, with alcoholic and malolactic fermentations. Residues in grapes were 1.4 and 1.6 mg/kg, decreasing in juice and wine, (processing factor (PF) of <0.01), in lees (PF 0.33) and in must (PF 0.81). Residues increased in raisins (PF 1.9), wet pomace (PF 2.0) and dry pomace (PF 3.6).

In four studies conducted in France, Spain and the USA, treated tomatoes were processed according to industrial manufacturing procedures. Residues in the tomatoes ranged from 0.09 to 0.86, decreasing after washing (PF 0.28, n=2), in juice (PF 0.22, n=2) and in purée (PF 0.44, n=4). Residues increased in tomato paste (PF 1.3, n=2), wet (PF 2.1, n=2) and dry pomace (PF 15, n=2).

Samples of treated winter barley from France and Germany were processed using traditional malting, brewing, milling and backing procedures. Residues were detectable only in pearling dust (PF 1.8) and in spent grain (PF 0.67). No residues (<0.02 mg/kg) were found in barley grits, pearl barley, wholemeal bread, malt, malt germ, trub, yeast (PF <0.5) or beer (PF <0.42, n=2).

Treated wheat from one site in France showed residues of 0.04 mg/kg, which increased in bran (PF 2). No residues (<0.02 mg/kg) were found in wholemeal, flour or wholemeal bread, with processing factors <0.5.

Residues in processed commodities

Estimates of residues in processed commodities were derived after multiplying the highest residue and/or STMR found in supervised trials on the raw commodity conducted according to GAP by the appropriate processing factor (PF) calculated from the processing studies. Maximum residue levels were only estimated for commodities of human consumption with a PF >1 with a Codex classification number and for commodities of animal consumption which can be used to estimate dietary burdens. An HR-P was estimated only when its use was required for the calculation of short-term exposure.

On the basis of a highest residue of 1.5 mg/kg and an STMR of 0.54 mg/kg in grapes the Meeting estimated an STMR-P of 0.005 mg/kg for famoxadone in wine and grape juice (PF 0.01), a maximum residue level of 5 mg/kg, an HR-P of 2.85 mg/kg and an STMR of 1.03 mg/kg for famoxadone in raisins (PF 1.9), and a maximum residue level of 7 mg/kg and an STMR of 1.94 mg/kg in dry pomace (PF 3.6).

On the basis of an STMR of 0.10 mg/kg for tomatoes the Meeting estimated an STMR-P of 0.022 mg/kg for famoxadone in tomato juice (PF 0.22), an STMR-P of 0.044 mg/kg for famoxadone in tomato purée (PF 0.44), and an STMR-P of 0.13 mg/kg for famoxadone in tomato paste (PF 1.3).

On the basis of an STMR of 0.02 mg/kg in barley, the Meeting estimated an STMR-P of 0.008 mg/kg for famoxadone in beer (PF 0.42) and an STMR-P of 0.01 mg/kg for famoxadone in wholemeal barley bread (PF 0.5).

On the basis of an HR of 0.04 mg/kg and an STMR of 0.02 mg/kg in wheat the Meeting estimated a maximum residue level of 0.2 mg/kg and an STMR-P of 0.04 for famoxadone in wheat bran (PF 2), and an STMR-P of 0.01 mg/kg for famoxadone in wheat flour and wheat wholemeal (PF 0.5).

Animal dietary burdens

The Meeting estimated the dietary burdens of famoxadone in cattle and poultry on the basis of the diets listed in Appendix IX of the FAO Manual (FAO, 2002) and the MRL and STMRs estimated at this Meeting.

Maximum dietary burden

STMR dietary burden

Animal feeding studies

Famoxadone was given in gelatin capsules twice daily to lactating Holstein dairy cows for 28 days at feeding levels of 9, 27 and 90 ppm. Three cows at each dose were slaughtered on day 29, and one at the higher feeding level was slaughtered on each of days 42 and 48.

In whole milk, residue levels of famoxadone reached a plateau by the tenth day of dosing at all doses. The mean plateau level (from day 10 to 28) was 0.14, 0.43 and 1.5 mg/kg at feeding levels of 9, 27 and 90 ppm respectively. The average residues from day 1 to day 28 were 0.12, 0.33 and 1.2 mg/kg. Residues in milk from the cow killed on day 48 (highest feeding level) decreased from 1.5 mg/kg at day 28 to 0.02 mg/kg at day 47. Mean residues in milk fat from day 14 to day 28 were 10 times those in whole milk (1.4, 4.3 and 15 mg/kg respectively).

In tissues, famoxadone residues were detected at day 28 in liver (average of 0.69, 2.0 and 6.3 mg/kg, at the low, medium and high doses respectively), kidney (0.15, 0.59 and 1.5 mg/kg), muscle (0.07, 0.24 and 1.0 mg/kg) and fat (1.0, 4.1 and 17 mg/kg). Tissues from the cow killed 20 days after the end of dosing had decreased to 0.04, 0.02, 0.01 and 0.19 mg/kg in liver, kidney, muscle and fat respectively

Residue levels in animal commodities

Cattle. The maximum dietary burdens of beef and dairy cattle estimated by the Meeting were 0.82 and 3.1 ppm respectively and the higher value of 3.1 ppm was used for calculation of the residues. The levels were derived by applying the transfer factor (residue level in milk or tissue ÷ residue level in diet) from the lowest feeding level (9 ppm) to the calculated maximum dietary burden. For the STMR estimate, the same procedure was applied to the STMR dietary burden for dairy cattle of 0.60 ppm.

As the residue levels of famoxadone reached a plateau rapidly in milk (<14 days), the maximum residue levels in tissues were derived from the maximum dietary burden by applying the transfer factor to the highest individual residue levels found in the feeding study (FAO Manual, 2002). The STMRs were derived from the STMR dietary burden and the mean residue levels. For milk, the mean residue at the plateau level from the 9 ppm feeding group was used to estimate both the maximum residue level and the STMR.

Assuming the milk to contain 4% fat, the mean concentration of famoxadone in milk fat, expressed as whole milk, is 0.019 mg/kg (0.48 ÷ 25).

The Meeting estimated a maximum residue level of 0.03 mg/kg (F) and an STMR of 0.009 mg/kg (F) for famoxadone in milks, a maximum residue level of 0.5 mg/kg, an STMR of 0.046 mg/kg and an HR of 0.24 mg/kg for famoxadone in edible offal (mammalian), and a maximum residue level of 0.5 mg/kg for famoxadone in meat (fat) (from mammals other than marine mammals).

For the purpose of dietary intake calculations, the Meeting estimated an STMR of 0.067 mg/kg and an HR of 0.41 mg/kg in fat from mammals other than marine mammals, and an STMR of 0.005 mg/kg and an HR of 0.031 mg/kg for famoxadone in muscle from mammals other than marine mammals.

Poultry. The metabolism study conducted with laying hens at 10 ppm in the feed (7 days dosing) showed no radioactive residues in muscle, fat, skin or egg white (<0.01 mg/kg). Radioactive residues were detected only in egg yolk and liver, with a maximum of 0.003 mg/kg famoxadone found in yolk. The feeding level in this study is almost 60 times the calculated maximum dietary burden for poultry (0.17 mg/kg feed).

The Meeting agreed that it is unlikely that famoxadone residues would remain in poultry tissues and eggs after the animal had been fed with commodities containing the fungicide. The Meeting estimated a maximum residue level of 0.01* mg/kg for famoxadone in poultry meat, poultry edible offal and eggs, and an HR and an STMR of 0 for famoxadone in poultry edible offal and eggs.

For the purpose of dietary intake calculations, the Meeting estimated an HR and an STMR of 0 for famoxadone in poultry muscle and fat.

DIETARY RISK ASSESSMENT

Long-term intake

The ADI for famoxadone is 0-0.006 mg/kg body weight/day. The international estimated daily intake (IEDI) was calculated for commodities of human consumption for which STMRs were estimated in this evaluation. The results are shown in Annex 3.

International Estimated Daily Intakes for the five GEMS/Food regional diets, based on estimated STMRs, ranged from 1 to 7% of the maximum ADI. The Meeting concluded that the intake of residues of famoxadone resulting from its uses that have been considered by the JMPR is unlikely to present a public heath concern.

Short-term intake

The International estimated short-term intakes (IESTI) for famoxadone were calculated for commodities for which STMR and HR values were estimated in this evaluation and for which data on consumption (large portion and unit weight) were available. The results are shown in Annex 4.

The acute RfD for famoxadone is 0.6 mg/kg bw. The IESTI represented 0 to 8% of the acute RfD for children and 0 to 3% of the acute RfD for the general population. The Meeting concluded that the short-term intake of residues of famoxadone from uses on the commodities that have been considered by the JMPR is unlikely to present a public health concern.